Tone generator



Feb. 7, 1961 G. M. MARR ETAL TONE GENERATOR 5 Sheets-Sheet 1 Filed Aug. 30, 1956 yea/y INVENTORS flf.

5 Shets-Sheet 2 Marv:

Geaiye eoxye G. M. MARR ETAL TONE GENERATOR Feb. 7, 1961 Filed Aug. 30, 1956 Feb. 7, 1961 G. MIMARR ETAL TONE GENERATOR 5 Sheets-Sheet 3 Filed Aug. 30, 1956 Feb. 7, 1961 e. M. MARR EI'AL TONE GENERATOR 5 Sheets-Sheet 4 Filed Aug. 30, 1956 5 Sheets$heet 5 Feb. 7, 1961 G. M. MARR ETAL TONE GENERATOR Filed Aug. 50, 1956 United States Patent TONE GENERATOR George M. Marr, 17040 Highland Ave., Jamaica 32, N.Y.,

and George A. Slatic, 1819 Summerfield Ave., Brocklyn 27, N.Y.

Filed Aug. 30, 1956, Ser. No. 607,069

4 Claims. (Cl. 340384) The present invention relates generally to sound producing devices for indicating position in a fog, and more particularly to an improved electric tone generator for creating bell, gong or horn like sounds when amplified suitably to warn the presence of a vessel in a fog.

Coast Guard regulations require that during the entire duration of fog, mist, falling snow, heavy rainstorms or other conditions restricting visibility, while the vessel is at anchor, a seaman must stand-by at the after part of the vessel with a stop watchin one hand, and with a hammer or mallet in the other and strike a metal gong at least Stimes every 60 seconds with an intermediate silent period of 55 seconds.

It is a principal object of the invention to provide a device which performs this signalling requirement automatically, dispensing with the need for the seaman who is freed to perform other duties.

It is a further objectof the invention to provide a warning signal device as an accessory to, and to be used in conjunction with, existing docking and navigating loud-speaker systems thereby reducing its cost.

Another object of the invention is to provide a tone generator which may be constructed to create one or more warning, signalling, alarm or musical tones preselected from the entire range of audio frequencies.

.Another object of the invention lies in the provision of a tone generator operable automatically at predetermined intervals.

Still another object of the invention is to provide a tone generator which is barely audible, the electrical output of which may be amplified and converted to produce sound'at a disance from the generator.

A still further object of the invention lies in the provision of a tone generator of simple, rugged and inexpensive construction requiring infrequent maintenance or repair.

The novel features that are considered characteristic of the invention are set forth with particularity in the appended claims.

Figure l is an elevational view of a tone generator for use as a fog gong constructed in accordance with the invention and showing the front of the device with the front cover removed;

Figure 2 is a sectional view taken on line 2-2 of Figurel and showing the internal parts of the generator in side elevation;

Figure 3 is a rear elevation of the tone generator shown with the rear cover removed;

Figure 4 is a bottom plan view of the tone generator with the lower wall of its casing shown partially broken away and taken on section-viewing line 4-4 of Fig. 1; Figure 5 is a schematic circuit diagram of the tone generator showing the internal connections and the man ner .of connecting to a shipboard amplifier and loudspeaker system;

Figure 6 is an elevational view of a second embodimentof the invention constructed for use as a combined ice fog bell and fog gong and showing the device with the front cover removed;

Figure 7 is a bottom plan view of the combined fog bell and gong taken on the section-viewing line 77 of Figure 6, and

Figure 8 is a schematic circuit diagram of the combined fog bell and gong showing the internal connections and the manner of connecting to an amplifier and loud-speaker system.

Referring now particularly to Figures 1-5 of the drawings, the tone generator for use as a fog gong and illustrated therein is housed in a rectangular casing 1 hav ing upper, lower, side, front and rear walls. The last two named cover walls have been removed and are not shown in the drawings for clarity of representation of the internal parts. A chassis 2 of angular configuration divides the interior of the easing into a number of vertical compartments and is secured by suitable fasteners to the side walls. The chassis extends nearly from top to bottom of the casing and serves to support most of the other parts to be hereinafter described.

A constant speed motor 3, preferably of the synchronous type, is geared down or otherwise connected by a gear reduction unit 4 to drive a timing gear 5 at one revolution per minute. The timing gear is mounted to rotate in a vertical plane and has a set of tooth-like protrusions 6 on its periphery. These teeth or cams 6 are 7 spaced approximately 6 apart and there are five cams in the set. Consequently, by this predetermined or selected positioning, the cams 6 serve to make an electric circuit once each second for five successive seconds by depressing the roller actuator 8 of microswitch 7. This microswitch is supported below the timing gear and its operating arm with the roller 8 bears upwardly against the periphery of the timing gear.

A second microswitch 9, having an operating arm with roller 10, is so disposed on the chassis 2 as to have the roller ride against the side of the rim of the timing gear 5. The timing gear is provided with a sideward protrusion 11 which extends for a minimum arc longer than that occupied by the set of cams 6, and is so p0- sitioned with respect to this set as to deflect the roller 10 and the operating arm of the switch 9 slightly before the firstcam 6 engages the roller 8. The cam 11 is adapted to make switch 9 and keep it made for the entire time the series of cams 6 make and break switch 7.

Aflixed to the vertical portion of chassis 2 is a horizontally extending floor member 12 which divides the in terior of the casing at one side' into upper and lower chambers. A rectifier 13, resistor 14 and capacitor 15 are supported from the floor member 12 in the lower chamber. Supported on the floor 12 and in the upper chamber is a relay 16 whose pivoted armature 17 is n0rmally biased upwardly to an open position as best shown in Figure 2. Fixedly secured to the armature, so as to move with it, is a hammer 18 having a downwardly extending arm 19 and a drum shaped head 20.

The frame of relay 16 at its lower end supports, by means of screws 21, a clamping block 22 which is split part of its length by a slot 23. This slot receives the lowermost end of a tone spring 25 which is firmly clamped by means of screws 24. The tone spring is preferably formed of flat ribbon spring steel .and extends vertically, held by the clamping block in position to be struck by the hammer head 20 when the relay is actuated. The thickness, length and material of the spring are chosen to obtain a desired resonant frequency of vibration. To aid in this and to conserve space, the free upper end of the tone spring is formed in a spiral coil 26, as best shown in Figure 2. In the illustrated embodiment, a spring having a resonant frequency of approximately cycles per second is preferred.

amino? A sound pickup 27, preferably but not necessarily of the reluctance type, is supported from the chassis and so positioned as to present the magnet ends close to the upper portion of tone spring 25 near the point where the spring spiral begins. The pick-up comprises a permanent magnet 29, in the shape ofja horseshoe, and a coil 28, wound about the two ends of the magnet. The tone spring is positioned between the. magnet ends 29 which are north and south magnetic poles, and is spaced slightly in front of the magnet faces so as to present a small air gap between thespring'25 and the magnet faces 29. The tone spring 25 is, therefore, a movable diaphragm and forms part of the magnetic circuit. Lines of magnetic flux flow from'one'pole of the magnet, across the air gap through the spring 25, across the air gap near the opposite pole, into the opposite pole and complete the circuit in the magnet to saidfirst pole. Movement of the diaphragm for spring 25 causes variations in the air gap and consequently varies the magnetic reluctance of the described circuit toinduce corresponding voltages in the coil 28. In this manner, each time the hammer 2t) strikes the tone spring 25 and causes it to vibrate at resonant frequency,a signal voltage of the same frequency is generated'in the pickup coil 28.

The wiring of the tone generator has been omitted from Figures l-4 to present unobstructed views'of the electrical and mechanical parts. In addition to those parts described above, there is shown the following: a spark suppressing capacitor 30 for. each 'micr'oswitch 7 and 9, an on-otf power switch 31of the toggle type supported on the top casing wall, a receptacleor socket 32 supported on the bottom casing wall and adapted to make six connections, a six conductor plug. 33 terminating a shielded cable 34, a power cable35,'insulatinggrommets 36 for passage of conductors through the chassis and casing walls, and a cable'support clamp 371cm the chassis 2..v

The circuit connections. of 'the described parts are schematically shown in Figure 5. The alternating current power leads 41 and 42 are respectively connected to the arm of switch .31 and to one side of the timing motor 3. The otherside of the motor is connected to switch terminal 43. Movement of the switch arm from terminal 44 to contact terminal 43 starts the motor. Each time one of the cams 6 on the timing gear makes the contact of microswitch7, a direct current pulse is fed to actuate relay 16 through conductor 41, switch 31 and terminal 43, con- .ductor 47, resistor 14, rectifier 13, relay coil 16, switch 7, conductor 48 and conductor 42.

One end of the pickup coil 28 is groundedto the shield of cable 34 and connected by conductor 49 to conductor 52 of cable 34. The other end of the pick coil is connected to terminal 45 of switch 31. Thus, the arm of switch 31, in its on position, leaves terminal 46 and contacts terminal 45 to make the amplifier input circuit which extends from the pickup coil 28 through conductor 51 of the shielded cable 34 to terminal 71 of plug 33, to the input of the amplifier, back to terminal 72, cable conductor .52 and conductor 49 to ground. Accordingly, signals generated in the pickup in response to resonant vibration of tone spring 25 are fed to the amplifier and thence from the amplifier output to the loud-speaker.

The loud-speaker is connected to the amplifier in series with the micro-switch 9 through plug terminal 73, cable conductor 53, conductors 83 and 84,. cable conductor 54 and plug terminal 74. Thus although the amplifier is normally switched on and kept Warm, the loud-speaker is connected only when switch contacts are made. This occurs periodically and during the entire time, the set of cams 6 are making switch 7 to actuate relay 16 and cause a series of vibrations of the tone spring and induced signals inthepickup, i ,7 .i

It should. be noted that receptacle terminals 62-66, respectively, are connected by cable conductors 52-56, respectively. 1..R e m n ls 7 :7 ecepta le terminal 61 is connected to plug terminal 71 by conductor 51, toggle switch 31 in off position and making'contact 46. This enables a sound powered microphone, not shown, having six terminal connections to be plugged into the receptacle 32 at the tone generator for speaking or signalling by voice through the amplifier and loud-speaker system. The microphone input circuit corresponds to terminals 61 and 62; the microphone Press to Talk circuit makes at terminals 63 and 64 while the microphone receiver circuit makes at terminals 65 and 6,6. I

To use the described device as an accessory fog warning instrument, cable 35 is plugged'into a power source, preferably a set of terminals on the amplifier of the vessels loud-speaker system. Plug 33 is connected to the amplifier. Both the amplifier switch and switch 31 are turned to on. An amplifier switch selecting the stern loud-speaker of the ship is turned on. As apparent from the above description, the timing motor 3 will start and once each minute, relay 16 will start and once each minute, relay 16 will be actuated by cams 6 a series of five 1 times at intervals of approximately one second. This will result in five strikings of the tone spring and induce a series of voltages in the pickup corresponding to the preselected resonant frequency of the spring. Accordingly, five gong like sounds (approximately 180 cycles per second) of one second duration each, and following each other instantaneously will be sounded from the stern loudspeaker. These will differ in frequency from the sound of the ships bellringing in the bow of the vessel in conipliance with the aforementioned Coast Guard regulations.

Referring now to Figures 6-8, there'is illustrated another embodiment of the invention which combines two tone generators to generate dissimilar sounds at preselected intervals, one simulating a gong and the other a bell. The combined fog bell and gong is housed in a rectangular casing 1a which is similar to but larger than casing 1 previously described for the, fog gong. An'angularchassis 2a--divides the chassis into four vertical compartments A, B, C and D. The chassis 2a extends nearly from top to bottom of the casing 1a and serves to support most of the parts contained therein.

Within the central chambers C and Dare supported a motor driven timing gear 5 and cam operated switches 7, 9 and 9a very similar to those for the fog gong alone, as previously described. Chamber C houses the motor 3, gear reduction unit 4, and a pair of microswitches9 and 9a. Microswitches 9 and 9a are alike butare diametrically disposed opposite each other with respect to the timing gear 5 which is supported in chamber B. The switches 9 and 9a are provided with actuatingrollers '10 and 10a which extend through openings in the chassis 2 1 to contact the side of the timing gear 5. The sideward protrusion 11 on the timing gear 5 is thus adapted to strike and deflect rollers 10 and 10a once each revolution so that the microswitches 9 and 9a operate each revolution but at different times. Timing gear 5 is provided with a set of cams 6 on its periphery which are adapted to strike roller Sand actuate a microswitch 7 in chamber B as heretofore described in connection with the fog gong illustrated in Figures 1-5.

Chambers A and D house a pair of tone generators similar to that previously described butv differing from each other in the pitch of the tones generated. On floor 12a in chamber A is supported a relay 16 which is in all respects similar to that shown in Figure 1 and which is adapted to strike a similar tone spring25 which generates a frequency of approximately 180 cycles per secjond in thepi'ckup' 27. The tone generator in chamber D diifer's from that in chamber A by the provision of a shorter tone spring 25a having a smaller spiral 26a at its upper free end. The frequency of the signal generated in pickup 27a is consequentlvhigherthan thatg'en'erated in'pickup'27 andis approximately 320 cycles per second.

Relay 16a is similar to relay 16 in all-respects except that it is provided with a set of interrupter contacts which are not shown inFigures 6 and?! but are illustrated in the circuit diagram of Figure 8. These contacts are leads 128 to 129 and 130 to 131.

made when the armature 17a is in its biased open position and are opened when the armature is attracted by current flowing in relay coil 16a. The duration of the opening spark is timed by means of chosen values of resistor 91 and capacitor 92, Figure 8, as will be further explained hereinafter.

The tone generators are each provided with identical relays 94 and 94a, each having six terminals 101-108, respectively, which seat in the sockets 95 carried by the floor members 12b in chambers A and D. As shown in Figure 8, these relays each have windings 96 connected across terminals 107 and 108, and actuation of the relays makes contacts, connecting terminal 102 to terminal 103 and terminal 105 to terminal 104 while simultaneously disconnecting terminals 101 and 106. Illustrated in Figures 6 and 7, without connecting wiring, are spark suppressing capacitors 30 for microswitches 7, 9 and 9a, a rectifier 13, resistors 14 and 97, and a capacitor 15. Insulating grommets 36 and 98 are provided for passage of conductors through the walls of the casing and chassis.

Figure 8 schematically illustrates the circuit connections of the described parts of the combined fog bell and gong. The cable 35 including alternating current power leads 41 and 42 energize the timing motor 3 through the following circuit: lead 41, connection 109, conductor 110, connection 111, conductor 112, the windings of motor 3, conductor 113, connection 114 and lead 42. When the motor 3 is energized by connecting leads 41 and 42 to a source of power, the timing gear revolves one revolution per minute. Each time one of the cams 6 on the timing gear 5 makes the contacts of microswitch 7, a direct current pulse is fed to actuate relay 16 through conductor 42, connection 114, conductor 47, resistor 14, rectifier 13, relay coil 16, connection 115, switch ,7, conductor 116, connection 111, conductor 110, connection 109 and lead 41.

When the relay 16 is energized by a direct current pulse, its armature 17 is attracted and moves the arm 19 and hammer 20 to strike the tone spring 25. Resonant vibration of the tone spring induces corresponding frequency signals in the coil of the pickup 27. One lead of the pickup coil 27 runs to a connection 117 which is grounded to the cable shield 118 and also connected to lead 120 to be connected to an amplifier (not shown).

The other lead of the pickup coil 27 is connected to a lead 119 also to be connected to the amplifier. Signals from the second pickup coil 27a are fed to the amplifier via the same leads 120 and 119 since the coil 27a is connected to them by connections 121 and 122, respectively.

During the entire time the set of cams 6 is actuating relay 16, cam 11 on the timer gear 5 strikes the roller of the microswitch 9 thereby closing its contacts. This establishes a circuit to energize relay 94 in the following manner. series circuit with resistor 14, rectifier 13 and the power source through leads 41 and 42, provides a direct current potential across its terminals or connections 123a and 109. This supplies energy to the winding 96 of the relay 94 from terminal 123a, through conductor 124, connection 125, conductor 126, terminal 108, winding 96, terminal 107, conductor 127, microswitch 9 contacts, connection 123 to terminal 109.

Energization of relay 94 makes the pairs of contacts 102-103 and 104105 and thereby connects amplifier The connection of lead 128 to 129 serves to actuate a relay, not shown, in the amplifier which in turn connects leads 120 and 119 across the amplifier input. The connection of 130 to 131 shorts a loud-speaker located in the bow of the ship, but permits amplified gong tones to be sounded through a speaker located in the stern of the ship.

Approximately one-half minute after the cams 6 of timing gear 5 have initiated the series of gong-like The bleeder resistor 97, being in a tacts. This energizes relay 16a by means of direct current potential across bleeder resistor 97, the circuit being from terminal 123a, through conductor 124, connection 125, conductor 126, connection 132, conductor 133, connection 134, closed relay contacts 90, terminal 135, relay winding 16a, terminal 136, closed contacts of switch 9a, conductor 137, connection 123, conductor 138 to terminal 109 of resistor 97. When relay 16a energized its armature 17a, it is actuated to swing arm 19a to strike hammer 20a against tone spring 25a causing it to vibrate at a relatively high resonant frequency which induces corresponding signals in the coil of pick-up 27a;

The coil of pickup 27a is connected across the amplifier leads 119 and 120, as previously described, so that the generated signals are fed to the amplifier input. These signals are intermittent, being interrupted by open ing of contacts when relay armature 17a is attracted. The values of resistor 91 and capacitor 92, which are connected to terminals 134 and across the contacts 90, are chosen to quench the spark in about one second during which time the tone spring 25a is vibrating. As soon as the current flow in the winding of relay 16a ceases, the armature 17a is again attracted causing the tone spring to be struck and the contacts 90 to open. This intermittent operation of the relay continues and repeats about five times during the time that cam 11 maintains switch 9a closed so that five signals of belllike frequency are fed to the amplifier.

bow of the 'ship is connected to the amplifier output in the following manner. Relay, 94a is energized, a circuit.

being completed from terminal 123a of bleedenzresisa tor 97, through conductor 124, connection 125, conductor 126, terminal 108, winding 96 and terminal 107 of relay 94a, conductor 139, terminal 136, contacts of switch 9a, conductor 137, connection 123, conductor 138 back to terminal 109 of resistor 97. Actuation of relay 94a closes its contacts 104105 connecting leads 140 and 141 which short out the stern loudspeaker. At the same time, relay contacts 102 and 103 are closed. These are paralleled with the corresponding contacts or terminals of relay 94 across lead- 128 and 129 which, as previously described, through an amplifier relay connect these leads across the amplifier input and result in sounding of the bell tones through the forward speaker. I

It will be readily understood from the foregoing description that the combined fog bell and gong will operate to sound five gong-like sounds (approximately cycles per second) from a ships stern loud-speaker of one second duration each. About twenty-five seconds later, five bell-like sounds (approximately 320 cycles per second) willbe generated to issue from the bow loudspeaker each of approximately one second duration. Approximately twenty-five seconds later, the above sequence repeats again. In this manner, the combined fog bell and gong, as a single instrument, enables compliance with the aforementioned Coast Guard regulations dispensing with the need for seamen at both ends of the ship to manually sound the required warnings.

While the invention has been described as applied particularly to the construction of a fog warning accessory device, it will be readily understood that its use is not limited thereto. The tone generator can be suitably designed to create appropriate sounds for many other purposes such as to mark factory starting, quitting and rest periods, school periods and periods of athletic contests. A number of tone generators according to the invention may be combined as an instrument to produce music. Its use as a burglar alarm is of particular advantage in that the sound generated in the tone generator is barely audible, if at all, and with the amplifier located at a dis,

germs? 7 tance, the burglar can be surprised and caught while unawaregthat an alarm is sounding.

While certain specific embodiments of the invention have been shown and described, it will be understood that numerous changes and modifications and the full use of equivalents maybe resorted to in the practice of theinvention without departing from the spirit or scope of the appended claims- That which is claimed as new is:

1. In a fog-warning apparatus for use with a ships public address system of the type which includes an amplifier, at least one stern mounted loudspeaker and at least one bow mounted loudspeaker, the combination of a first vibratory means adapted when struck to vibrate at a resonant frequency and generate a gong-like tone, a second vibratory means adapted when struck to vibrate at a resonant frequency and generate a bell-like tone, a pair of electromagnetically operated hammers arranged to strike said first and second vibratorymeans respectively, a

pair of magnetic pickups juxtaposed said vibratory means, a timing mechanism including a motor for turning a single timing wheel, a pair of switches adjacent said wheel, a single cam on said wheel adapted to close said pair of switches at different times, a pair' of relays operated by said pair of switches, a series of cams on said wheel adapted to close a third switch and operate one of said electromagnetic hammers to strike said first vibratory means and generate a series of gonglike tones, interrupter means connected with said other electromagnetically operated hammer to operate the hammer intermittently and develop a series of bell-like-tones when the hammer is energized by the closing of one of said pair of switches, and a pair of relays individually op- ;erated bysaid pair of switches to connect one pickup to said amplifier and stem speaker while simultaneously disconnecting said how. speaker and to' connect the other pickupLtosa-Zd amplifier .and bow speaker whilesimultaneously disconnecting said stern speaker.

2. In a fog-warning apparatus for use with a ships public address system o'f'the type which includes an amplifier, at least one stern mounted loudspeake and at least one bow mounted loudspeaker, the combination of a first vibratoryrneans adapted when struck to vibrate at 'a resonant frequency and generate a gong-like tone, a second vibratory means adapted when struck to vibrate at a resonant frequency and generate a bell-like tone, a

pair of electromagnetically operated hammers arranged to strike said first and second vibratory means respectively, a pair of magnetic pickups juxtaposed said vibraand generate a series of gonglike tones, interrupter means connected with'said other electromagnetically operated hammer to operate the hammer intermittently and develop a series of bell-like tones when the hammer is energized by closing of one of said pair of switches to sequentially connectone pickup to said amplifier and stern speaker while simultaneously disconnecting said how speaker and to connect the other pickup to said amplifier and bow speaker while simultaneously disconnecting said stern speaker.

3. Ina fog-warning :apparatus for use with a ships public address system of the type which includes an amplifier and at least one loudspeaker mounted in the bow or stern, the-combination of a vibratory means adapted when struck to vibrate at a resonant frequency and generate'a warning tone, an electromagnetically operated hammer arranged to strikesaidvibratory means, a magnetic pickup juxtaposed said yibratory means, a timing mechanismincluding a motorfor turning a single timing wheel, a pair of switches adjacent said wheel, a cam on the side of said wheeladapted to close one of said pair of switches, a series of cams on the periphery of said wheel adapted to close said other switch and operate said electromagnetic hammer to strike the vibratory means and generate a series of gonglike tones, means forconnecting said pickup to said amplifier, said one switch when closed by said cam on the side of the timing wheel connecting said speaker to the amplifier, and said cam being so formed as to close said switch during the whole time period required for said-peripheral series of cams to move past the hammer operating switch.

4. In a fog-warning apparatus for use with a ships public address system of the type which includes an amplifier and at least one loudspeaker mounted in the stem or 'bow, the combination of a vibratory member'adapted when struck to,,vibrate at a resonant frequency and generate a warning tone, an electromagnetically operated hammer arranged to strike said vibratory member, a magnetic pickup juxtaposed said vibratory -member,-a timing mechanism including a motor and a timing'element, and means on said timing element for controlling the energizing of said electromagetically opera-ted hammer in a series of pulses to strike the hammer against said vibrating member in a series of blows and simultaneously connect said pickup to saidpublic address system.

References Cited in the file of this patent UNITED STATES PATENTS 1,753,069 Schumm Apr. 1, 1930 1,871,636 Trogner Aug. 16, 1932 1,960,079 Bossard May 22, 1934 2,026,342 Curtiss Dec. 21, 1935 2,286,587 Sundt June 16, 1947 2,522,664 Coleman Sept. 19, 1950 2,657,375 Paul Oct. 27, 1953 

